The present invention relates to an image correction system for a cathode ray tube (CRT) display such as a color television receiver or a display terminal and, particularly, to a digital image correction device for use in a multi-mode CRT display device having a plurality of display modes which are different from each other in electron beam deflecting condition.
As an example of a conventional digital image correction device, a digital convergence correction device responsible to any of a plurality of signal specifications is disclosed in Japanese Patent Application Laid-open (Kokai (P)) No. 61-222392.
In the disclosed digital convergence correction device, convergence correction data of regulation points are stored in a memory and the read address timing is controlled by respective input signals so that the location of regulation point on an image screen is always maintained fixed. However, this prior art is silent as to the difficulty of maintaining the regulation point at such fixed location by independently controlling timing of the respective regulation points. Further, in such system in which all of regulation points are controlled evenly, accuracy of correction is not enough, and thus it is necessary to reregulate them for every input signal or every change of raster size.